1. Field of the Invention
The present invention relates to a resist pattern-forming method, and a radiation-sensitive resin composition.
2. Discussion of the Background
Miniaturization of various types of electronic device structures such as semiconductor devices and liquid crystal devices has been accompanied by demands for miniaturization of resist patterns in lithography processes. Although fine resist patterns having a line width of about 90 nm can be formed using, for example, an ArF excimer laser at present, finer resist pattern formation is required in the future.
On the other hand, high resolving abilities can be reportedly attained according to liquid immersion lithography, even if a light source of the same exposure wavelength is employed, similarly to the case in which a light source of a shorter wavelength is employed in conventional resist pattern formation. Thus, the liquid immersion lithography has drawn attention as a technique that achieves high resolution in manufacturing semiconductor elements which require a large amount of investment in equipment while suppressing an increase in costs.
However, due to elution of substances included in a resist into a liquid immersion medium, and the like in liquid immersion lithography, disadvantages have been presumed that adversely affect lithography characteristics by way of: deterioration of the resist film to impair performances thereof; regional changes of a refractive index of the liquid immersion medium due to eluted substances; contamination of the surface of a lens from eluted substances; and the like (see pamphlet of PCT International Publication No. 2004/068242). In order to avoid the disadvantages, it has been suggested to increase hydrophobicity of a resist film; however, this modification requires an alteration of a resist composition, and such changes commonly tend to deteriorate lithography characteristics.
In addition, as a technique for increasing resolving power utilizing characteristic features of chemically amplified type resist materials, a technique in which a developer solution is used which is an organic solvent having lower polarity than that of aqueous alkali solutions has been disclosed (see Japanese Unexamined Patent Application, Publication No. 2000-199953).